Table 1.
Influence of kelp forest status (fixed categorical covariate with two levels: healthy and degraded) and season (fixed categorical covariate with four levels) on the α-biodiversity of seaweed assemblages found at golden kelp stands. Values are from Wald χ2 tests for the fixed terms fitted with a generalized linear mixed model (GLMM); σ2 for sampling reef as a random intercept nested in season was 0.042 for species density and 0.009 for diversity; d.f. = degrees of freedom. Significant P-values are shown in bold.
| Reef richness (species per reef) | Species density (species per 0.25 m2) | α-Diversity (Shannon, ln) | |||||
|---|---|---|---|---|---|---|---|
| Fixed effects | d.f. | Wald χ2 | P-value | Wald χ2 | P-value | Wald χ2 | P-value |
| Kelp forest status = St | 1 | 0.603 | 0.4374 | 0.264 | 0.607 | 0.147 | 0.701 |
| Season = Se | 3 | 52.75 | <0.0001 | 130.78 | <0.0001 | 95.06 | <0.0001 |
| Se × St | 3 | 5.90 | 0.1168 | 27.37 | <0.0001 | 11.62 | 0.0088 |
| Model | Negative binomial (log link), dispersion modelled as a function of St | Poisson (log link) | Gaussian (log link), dispersion modelled as a function of St | ||||